speed restriction?
 

hi all. I sometimes hear pilots request "cancel speed restriction" in countrys like Australia, do they mean to cancel the 250knot restriction and accelerate to ECON climb speed?

and could anyone explain to me why we have speed restriction? I mean if we have SID and STAR, traffic would be more organised and therefore the flow can be faster and accomodate more traffic.

Not an ATC thing but most aircraft have a birdstrike speed restriction at lower levels. Ours is 313 knots below 8000'.

I imagine if the speeds are too high in a terminal area, ATC may struggle to stay on top of things if they're happening too quickly.

Just a couple of examples...

You havent lived until youve pulled a Whale 370 knots at
3000ft 15nm from the runway at MLW on approach! :ok:

I believe the 250 Kt. speed restriction was initially introduced in the United States following a fatal collision between a United Airlines DC-8 and a TWA Lockheed Constellation in The New York terminal area, This happened in December 1960, it's use has spread to most countries and is incorporated into The ICAO airspace requirements, certain countries( like Australia) will often give pilots a waiver on this requirement when requested , normally with minimal traffic around.....nothing like a B727 @ 350kts. to 20 nm.!!

Remembering that in Class G airspace, i.e. outside Controlled Airspace, in the U.K., 250kts below 10,000ft is a legal requirement........

Folks,
There are three kinds of "speed restrictions", regulatory, procedural and recommended. The last is somewhat rare these days, and not as important as the first two, but don't ignore one without careful consideration.

As has already been mentioned, the 250 below 10,000 in E and G in Australia is a regulatory limit, the only time you can exceed it is if there is a safety issue. "ATC" CANNOT give any kind of a release or waiver for a statutory speed restriction --- so don't bother asking. But please tell them when you are going to exercise your authority as PIC to exceed 250 below 10,000 --- for a provable safety reason.

The "speed limits" in D and C airspace in Australia are procedural, ATC can waive them when traffic permits. The PIC can decline to accept the ATC speed if it is a matter of operational safety, say a 290 kt minimum turbulence speed and there is turbulence.

Likewise, if it is a matter of operational safety (NOT commercial convenience/time saving) the PIC can exceed the 250 kt limit in E and G. Don't forget there is an evidential burden on the PIC to prove the breach was a safety issue;ie; guilty until proven innocent.

The US 250 below 10,000 (read the whole rule, FAR 91.117, very carefully if you are flying in US airspace) is regulatory, and applies to all classes of US airspace, which really means B, C and E, as there is very little G in the lower 48. Again, ATC CANNOT give a waiver or release from this restriction,(legally, ATC do not have a power to give an exemption from a regulation - to waive the law) but there is provision for the PIC to decide to exceed 250kt, if it is a matter of operational safety. See FAR 91.117(d).

250 below 10,000 is NOT the only statutory speed limit in US, read the rule very carefully. See the application of the 200kt limit, FAR 91.117 (b) & (c).

A number of countries have a mix of one or more of statutory, procedural and recommended speed, make certain you know what you are dealing with.

Tootle pip!!

Yes. Jets operate best at their ECON speed, so climbing (or descending) at 250KIAS is not desirable. If you're running late, then climbing faster than 250 will help. At some ports in Australia where there are two restrictions, 250 below 10,000ft and also 250 on the SID/STAR, if ATC cancel the SID or STAR (meaning that the SID/STAR speed restriction is also cancelled) you will often hear pilots ask for a "cancellation of the speed restriction below 10,000" as well, because otherwise that would still apply.

The accident that resulted in 250 kias below 10,000' happened in 1967.

TWA Flight 553 - Wikipedia, the free encyclopedia

250 knots below 10,000 feet is mandatory in all airspace classifications which rely on "see and avoid" to separate the traffic permitted to fly within them. That's ICAO class C, D, E, F & G. This speed limit is a mandatory requirement of the airspace and may not be relaxed by ATC.

ATC may relax restrictions in class A and B.

That's correct, in a roundabout way ("C" does not wholly rely on "See and Avoid"). In ICAO C, IFR has no speed limits. Only VFR has a 250k < 10,000' limit.

Checkboard
 

I have been searching for this text as I have read it before. Could you tell me where it is from?

Cheers

Unless the State allows otherwise.

In the UK, ATC may relax the restriction in Class D since it is a known traffic environment.

There is no restriction in Class C in the UK since it only exists above FL195.

The UK has no Class B.

There is no restriction in Class A in the UK, except where specifically mentioned in the AIP, e.g. on SIDs and STARs or within TMAs. So if you're flying along a Class A Airway below FL100 and there are no AIP restrictions, then you can fly above 250Kts if you wish.

Finally, the UK CAA will also issue dispensations for non compliance with the speed restrictions. Mostly these are for historical display or test aircraft.

Full chapter and verse for UK procedures can be found here:

UK AIC - Airspace Speed Limits

Page 60 of this PDF document shows the speed limits in ICAO airspace. I assume it is still current.

Thanks for the ref..